Patent Document 1 discloses a cylinder head gasket 80 that is shown in FIG. 7 of the present application. The cylinder head gasket 80 is a metal gasket having a laminated structure. The cylinder head gasket 80 has an intermediate plate 81 and an adjustment plate 82 that are laminated on each other, and bead plates 83, 84 that sandwich the intermediate plate 81 and the adjustment plate 82. The intermediate plate 81 and the cylinder head sandwich the bead plate 83 and the adjustment plate 82 and the cylinder block sandwich the bead plate 84.
The cylinder head gasket 80 has a plurality of combustion chamber openings 80a each of which corresponds to one of the cylinder bores formed in the cylinder block. The bead plates 83, 84 have beads 83a, 84a each of which surrounds the combustion chamber opening 80a. If the cylinder head is fixed to the cylinder block by a bolt in a state where the cylinder head gasket 80 is provided between contact surfaces of the cylinder head and the cylinder block, the bead 83a seals a space between the cylinder head and the intermediate plate 81, and the bead 84a seals a space between the cylinder block and the adjustment plate 82.
The intermediate plate 81 has a stopper portion 81a that is provided around the combustion chamber opening 80a. The stopper portion 81a receives axial fastening force of the bolt to inhibit the beads 83a, 84a from fully collapsing. That is, the stopper portion 81a compensates for the space between the contact surfaces of the cylinder head and the cylinder block that is formed by deformation of the cylinder head gasket 80 due to the fastening force of the bolt. The adjustment plate 82 adjusts the thickness of the cylinder head gasket 80 such that the thickness of the cylinder head gasket 80 becomes equal to the space between the contact surfaces of the cylinder head and the cylinder block. The adjustment plate 82 has a recess 82a to which the stopper portion 81a is fitted. In the above publication, the intermediate plate 81 is referred to as a “compensation plate”, and the stopper portion 81a is referred to as a “folded portion”.
The thickness of the stopper portion 81a is greater than the thickness of other portions of the intermediate plate 81. The stopper portion 81a protrudes along its thickness toward the adjustment plate 82. A step 81b is formed between the stopper portion 81a and the other portions of the intermediate plate 81. The measurement along the thickness between the intermediate plate 81 and the stopper portion 81a is referred to as a stopper height H1, and the measurement along the thickness of the recess 82a is referred to as an adjustment step height H2. The stopper height H1 is greater than the adjustment step height H2.
Therefore, when the cylinder head is fastened to the cylinder block with the bolt, the stopper portion 81a closely contacts the adjustment plate 82. However, a space T is formed between the intermediate plate 81 and the adjustment plate 82 in the vicinity of the step 81b. If the cylinder head gasket 80 receives pressure fluctuation in the cylinder bore or the repetition of cooling and heating in a state where the space T is formed, the adjustment plate 82 may flap.
Patent Document 1: Japanese Laid-Open Patent Publication No. 7-55005